A- plane mirror because its surface is plane
Answer:
The pressure is 
Explanation:
From the question we are told that
The gauge pressure at the mouth is 
The radius of the column is 
The speed of the liquid outside the body is 
The area of the column is 
The area inside the mouth 
Generally according to continuity equation

=> 
=> 
=> 
So

=> 
=> 
substituting values


Now the height of inside the mouth is 
Now the height of the column is 
Generally according to Bernoulli's equation
![p_1 = [\frac{1}{2} \rho v_2^2 + h_2 \rho g +p_2] -[\frac{1}{2} \rho * v_1^2 + h_1 \rho g ]](https://tex.z-dn.net/?f=p_1%20%3D%20%20%5B%5Cfrac%7B1%7D%7B2%7D%20%20%5Crho%20v_2%5E2%20%2B%20h_2%20%5Crho%20g%20%2Bp_2%5D%20-%5B%5Cfrac%7B1%7D%7B2%7D%20%5Crho%20%2A%20v_1%5E2%20%2B%20h_1%20%5Crho%20g%20%5D)
Now
which is the density of water
is the gauge pressure of the atmosphere which is zero
So
![p_1 = [(0.5 * 1000 * (3.1)^2) +(0.008 * 1000 * 9.8) + 0]-](https://tex.z-dn.net/?f=p_1%20%3D%20%20%5B%280.5%20%2A%201000%20%2A%20%283.1%29%5E2%29%20%2B%280.008%20%2A%201000%20%2A%209.8%29%20%2B%200%5D-)

Answer:
Speed = 575 m/s
Mechanical energy is conserved in electrostatic, magnetic and gravitational forces.
Explanation:
Given :
Potential difference, U = 
Mass of the alpha particle, 
Charge of the alpha particle is, 
So the potential difference for the alpha particle when it is accelerated through the potential difference is

And the kinetic energy gained by the alpha particle is

From the law of conservation of energy, we get





The mechanical energy is conserved in the presence of the following conservative forces :
-- electrostatic forces
-- magnetic forces
-- gravitational forces
If its just a number 2,300 is an answer